Frontend Engineer — Based in Spain, working remotely
I build fast, purposeful websites and digital products.
Design-trained. Product-minded. I work with agencies, startups and marketing teams that need more than someone who writes good code.
About
More than a frontend developer.
I'm Juan Carlos, a freelance frontend engineer based in Spain, working remotely with agencies and companies across the UK, Europe and beyond.
Design background. Product mindset. I build websites, landing systems and product interfaces where execution and business results both matter.
Available for freelance work.
What I do
What I bring to a project.
I'm not just a developer who implements designs. I come with opinions about structure, performance, conversion and what makes a website actually work for a business.
High-performance websites
Modern, fast websites built with Astro and React. SEO-ready, easy to maintain, and designed to last longer than the project brief.
Landing pages & conversion systems
Pages for campaigns, launches and lead generation. I've worked with marketing and affiliate clients — performance and conversion are not optional.
Product interfaces
Turning ideas and flows into clean, consistent interfaces. I think in components, states and systems — not isolated screens.
Design systems & UI foundations
Reusable component bases and token structures that let teams move faster without starting from scratch every time.
Frontend architecture
Monorepos, shared packages, scalable structures. I care about how things are built — not just that they work today.
How my work is organised
Three connected layers.
My work lives across three spaces — each with a different purpose, all feeding into each other.
JCENLO
Personal layer
This site — where I write, share experiments and think out loud about building for the web.
ENLOLAB
Studio layer
Where client work lives. Websites, product interfaces and digital experiences built with agencies and companies.
SAASTRO
Technology layer
Tools, components and infrastructure I'm building — form systems, website workflows and product foundations.
Stack
What I build with.
Design
- Figma
- Adobe
Frontend
- React
- TypeScript
- Tailwind
- shadcn
Web
- Astro
Data & APIs
- tRPC
- Zod
Backend
- Node
- Fastify
AI
- Claude
- OpenAI
Every tool here because it improves performance or reduces friction.
Notes
On building for the web.
I write occasionally about frontend architecture, performance, product thinking and working with AI as a real part of the process.
All notes →Why I no longer use Figma
How I went from designing screens to writing prompts, and why a pencil and paper give me more than any design tool.
saastro-relay: persistent memory for working with AI on real projects
Every AI session starts from zero. saastro-relay is the MCP server I built to fix that: it syncs context and code snapshots between Claude.ai and Claude Code with a dual local + cloud architecture.
Design systems with AI: what changes and what doesn't
AI speeds up interface generation, but a design system still needs human judgement. How I integrate AI tools into my workflow without losing coherence.
UX writing: words are interface
Copy is not decoration added at the end. It's a design decision with the same weight as spacing, color, or hierarchy.
Collaborations
Who I work well with.
I'm interested in projects where design, frontend and product need to work together properly. I prefer a small number of good collaborations over a high volume of scattered work.
For professional studio work → enlolab.com
Agencies and studios that need strong frontend with product thinking — not just implementation.
Marketing and affiliate teams that need fast, well-structured websites built to convert.
Startups building digital products that need someone who understands both the interface and the architecture underneath.
Companies with an existing product that needs better frontend foundations, performance or UX.
Projects where design quality, technical execution and business results all need to work together.
Contact
Let's talk.
If you're building something and think I could help — a website, a product interface, a campaign landing system, or something that doesn't fit neatly into a category — get in touch.
I'm particularly interested in projects where design quality, technical execution and business results all need to work together.